MRI for Acute Pelvic Pain in Pediatric Females After Inconclusive Ultrasound: Diagnostic Performance of...

Background/Objectives: Acute pelvic pain in pediatric female patients is a common presentation in the emergency setting and poses significant diagnostic challenges. Ultrasonography is the first-line imaging modality, but a substantial proportion of examinations remain inconclusive. Magnetic resonance imaging (MRI) is increasingly used as a second-line modality in this context; however, evidence comparing the diagnostic performance of non-contrast-enhanced and contrast-enhanced MRI protocols in pediatric patients remains limited. The aim of this study was to assess the diagnostic accuracy of MRI in pediatric females with acute pelvic pain after inconclusive ultrasonography and to compare non-contrast-enhanced and contrast-enhanced MRI protocols. Methods: This single-center observational study included pediatric female patients presenting with acute pelvic pain who underwent MRI after inconclusive ultrasonography. MRI examinations were performed using a standardized protocol including non-contrast-enhanced sequences and diffusion-weighted imaging. Administration of contrast material was determined by the attending radiologist according to clinical indications. Three radiologists with different levels of experience independently reviewed all examinations in two separate reading sessions (without and with contrast). Diagnostic performance, interobserver and intraobserver agreement, diagnostic confidence, and examination duration were assessed using a composite clinical reference standard. Results: Eighty-eight patients (mean age, 13.5 years; range, 7-17 years) were included. MRI identified a specific cause of acute pelvic pain in 60 patients (68.2%), with gynecological conditions accounting for 75.0% of positive findings. Hemorrhagic ovarian cysts and adnexal torsion were the most frequent diagnoses. Both non-contrast-enhanced and contrast-enhanced MRI demonstrated high diagnostic accuracy across all readers, with no statistically significant differences in sensitivity or specificity between protocols (p > 0.05). Contrast-enhanced MRI was associated with higher diagnostic confidence for all readers (p < 0.001) but longer examination times. Conclusions: MRI is a reliable second-line imaging modality for evaluating acute pelvic pain in pediatric female patients after inconclusive ultrasonography. Non-contrast-enhanced MRI combined with diffusion-weighted imaging provides robust diagnostic performance in most cases, while contrast-enhanced MRI may be reserved for selected equivocal cases.